Spare tyre

[brad]

The only thing that needs it is an aeroplane as Nitrogen is inert and doesnt pressure up at altitude.

The primary reason for its use on aircraft is safety, as nitrogen does not support combustion.

Nitrogen, like other gases, follows the ideal gas laws - that is, pressure is directly proportional to temperature for a fixed mass and volume (for instance, the inside a tyre, which is close enough).

Both are correct.

Plus, when using Nitrogen, you don't get a chunk of ice forming in the low point of tyre causing a massive wheel imbalance / flat spot on landing.

[spud75]

The primary reason for its use on aircraft is safety, as nitrogen does not support combustion.

Nitrogen, like other gases, follows the ideal gas laws - that is, pressure is directly proportional to temperature for a fixed mass and volume (for instance, the inside a tyre, which is close enough).

Correct. The only difference pure nitrogen will make is the 22% left over. Which has 20% O2 and then everything else. Pure Nitrogen is supposed to minimize the amount of "air" lost through the rubber as well as be more stable as temperatures change. Considering the mass of O2 is greater than Nitrogen, the molecules are bigger so less will be lost through the walls anyway.

Yes O2 is combustible or provides the combustion of other materials, so you remove that from the equation in a plane.

In F1, they are concerned about that 2% that is left over. Hence the desire for a pure gas in the tyres for a level baseline and to remove outside factors well looking for 100ths of a second.

If they are filling the tyres for you with Nitrogen, do they extract all the air in the tyres first to crate a vaccuum then fill with Nitrogen? If not then you still have a component that is not pure Nitrogen anyway. Just a larger percentage of Nitrogen per volume.

If you really want better performance from your tyres, forget nitrogen, instead regularly check the pressures with a non-service station pressure gauge. Always use the same gauge for consistency and alter accordingly. Bearing in mind outside air temp, driving distance and speed will all affect the pressure.